X-Git-Url: https://git.donarmstrong.com/?a=blobdiff_plain;f=scm%2Flayout-page-layout.scm;h=8a7628af857519d7c1dc0ec0bb8c718db029ab27;hb=9f3572d98bb948c9689cd1f75401a029451fa001;hp=e370a171323254050179f6e777eea2bece37b859;hpb=04265f11d1f21416ccebd2dcaa1d903dc781b36e;p=lilypond.git

diff --git a/scm/layout-page-layout.scm b/scm/layout-page-layout.scm
index e370a17132..8a7628af85 100644
--- a/scm/layout-page-layout.scm
+++ b/scm/layout-page-layout.scm
@@ -1,219 +1,148 @@
-;;;; layout-page-layout.scm -- page breaking and page layout
+;;;; page-layout.scm -- page breaking and page layout
 ;;;;
 ;;;;  source file of the GNU LilyPond music typesetter
 ;;;;
 ;;;; (c) 2004--2006 Jan Nieuwenhuizen <janneke@gnu.org>
-;;;;	      Han-Wen Nienhuys <hanwen@xs4all.nl>
-
-(define-module (scm layout-page-layout)
-  #:use-module (srfi srfi-1)
-  #:use-module (oop goops describe)
-  #:use-module (oop goops)
-  #:use-module (scm paper-system)
-  #:use-module (scm page)
-  #:use-module (scm layout-page-dump)
-  #:use-module (lily)
-  #:export (post-process-pages optimal-page-breaks make-page-from-systems
-	    page-breaking-wrapper
-	    ;; utilities for writing custom page breaking functions
-            line-height line-next-space line-next-padding
-	    line-minimum-distance line-ideal-distance
-	    first-line-position
-	    line-ideal-relative-position line-minimum-relative-position
-            line-minimum-position-on-page stretchable-line?
-	    page-maximum-space-to-fill page-maximum-space-left space-systems))
-
-(define (page-breaking-wrapper paper-book)
-  "Compute line and page breaks by calling the page-breaking paper variable,
-  then performs the post process function using the page-post-process paper
-  variable. Finally, return the pages."
-  (let* ((paper (ly:paper-book-paper paper-book))
-         (pages ((ly:output-def-lookup paper 'page-breaking) paper-book)))
-    ((ly:output-def-lookup paper 'page-post-process) paper pages)
-    pages))
+;;;;          Han-Wen Nienhuys <hanwen@cs.uu.nl>
+
+(use-modules (oop goops describe)
+	     (oop goops)
+	     (scm paper-system)
+	     (scm page)
+	     )
+
+
+(define (write-page-breaks pages) 
+  "Dump page breaks"
+
+  (define tweaks (make-hash-table 23))
+
+  (define (record what property-pairs)
+    (let*
+	((key (ly:output-def-lookup (ly:grob-layout what)
+				    'tweak-key
+				    "tweaks"
+				    ))
+	 (when (ly:grob-property what 'when))
+	 )
+
+      (if (not (hash-ref tweaks key))
+	  (hash-set! tweaks key '()))
+
+      (hash-set! tweaks key
+		 (acons when property-pairs
+			(hash-ref tweaks key)))
+      
+      ))
+
+  (define (graceless-moment mom)
+    (ly:make-moment
+     (ly:moment-main-numerator mom)
+     (ly:moment-main-denominator mom)
+     0 0))
+
+  (define (moment->skip mom)
+    (let*
+	((main (if (> (ly:moment-main-numerator mom) 0)
+		   (format "\\skip 1*~a/~a"
+			   (ly:moment-main-numerator mom)
+			   (ly:moment-main-denominator mom))
+		   ""))
+	 (grace (if (< (ly:moment-grace-numerator mom) 0)
+		    (format "\\grace { \\skip 1*~a/~a }"
+			    (- (ly:moment-grace-numerator mom))
+			    (ly:moment-grace-denominator mom))
+		    "")))
+
+      (format "~a~a" main grace)))
+    
+  (define (dump-tweaks out-port tweak-list last-moment)
+    (if (not (null? tweak-list))
+	(let*
+	    ((now (caar tweak-list))
+	     (diff (ly:moment-sub now last-moment))
+	     (these-tweaks (cdar tweak-list))
+	     (skip (moment->skip diff))
+	     (line-break-str (if (assoc-get 'line-break these-tweaks #f)
+				 "\\break\n"
+				 ""))
+	     (page-break-str (if (assoc-get 'page-break these-tweaks #f)
+				 "\\pageBreak\n"
+				 ""))
+	     (space-tweaks (format "\\spacingTweaks #'~a\n"
+				   (with-output-to-string
+				     (lambda ()
+				       (pretty-print
+				   
+					(assoc-get 'spacing-parameters these-tweaks '()))))
+				     ))
+	     (base (format "~a~a~a"
+			   line-break-str
+			   page-break-str
+			   space-tweaks))
+	     )
+
+	  (format out-port "~a\n~a\n" skip base)
+	  (dump-tweaks out-port (cdr tweak-list) (graceless-moment now))
+	)))
+
+  (define (dump-all-tweaks)
+    (let*
+     ((paper (ly:paper-book-paper (page-property  (car pages) 'paper-book)))
+      (parser (ly:output-def-parser paper))
+      (name  (format "~a-page-layout.ly"
+		     (ly:parser-output-name parser)))
+      (out-port (open-output-file name)))
+      
+     (ly:progress "Writing page layout to ~a" name)
+     (hash-for-each
+      (lambda (key val)
+	(format out-port "~a = {" key)
+	(dump-tweaks out-port (reverse val) (ly:make-moment 0 1))
+	 (display "}" out-port))
+       tweaks)
+     (close-port out-port)
+     ))
+
+  (define (handle-page page)
+    (define index 0)
+    (define music-system-heights
+      (map-in-order (lambda (sys)
+		      (* -1 (car (paper-system-extent sys Y))))
+		    (remove (lambda (sys)
+			      (ly:prob-property? sys 'is-title))
+			    (page-lines page))))
+    (define (handle-system sys)
+      (let*
+	  ((props `((line-break . #t)
+		    (spacing-parameters
+		     . ((system-Y-extent . ,(paper-system-extent sys Y))
+			(system-refpoint-Y-extent . ,(paper-system-staff-extents sys))
+			(system-index . ,index)
+			(music-system-heights . ,music-system-heights)
+			(page-system-count . ,(length (page-lines page)))
+			(page-printable-height . ,(page-printable-height page)) 
+			(page-space-left . ,(page-property page 'space-left))))
+		    )))
+
+	(if (equal? (car (page-lines page)) sys)
+	    (set! props (cons '(page-break . #t)
+			      props)))
+	(if (not (ly:prob-property? sys 'is-title))
+	    (record  (ly:spanner-bound (ly:prob-property sys 'system-grob) LEFT)
+		     props))
+
+	(set! index (1+ index))
+	))
+    (for-each handle-system (page-lines page)))
+
+  (for-each handle-page pages)
+  (dump-all-tweaks))
 
 (define (post-process-pages layout pages)
-  "If the write-page-layout paper variable is true, dumps page breaks
-  and tweaks."
   (if (ly:output-def-lookup layout 'write-page-layout #f)
       (write-page-breaks pages)))
 
-;;;
-;;; Utilities for computing line distances and positions
-;;;
-(define (line-height line)
-  "Return the system height, that is the length of its vertical extent."
-  (interval-length (paper-system-extent line Y)))
-
-(define (line-next-space line next-line layout)
-  "Return space to use between `line' and `next-line'.
-  `next-line' can be #f, meaning that `line' is the last line."
-  (let* ((title (paper-system-title? line))
-	 (next-title (and next-line (paper-system-title? next-line))))
-    (cond ((and title next-title)
-	   (ly:output-def-lookup layout 'between-title-space))
-	  (title
-	   (ly:output-def-lookup layout 'after-title-space))
-	  (next-title
-	   (ly:output-def-lookup layout 'before-title-space))
-	  (else
-	   (ly:prob-property
-	    line 'next-space
-	    (ly:output-def-lookup layout 'between-system-space))))))
-
-(define (line-next-padding line next-line layout)
-  "Return padding to use between `line' and `next-line'.
-  `next-line' can be #f, meaning that `line' is the last line."
-  (ly:prob-property
-   line 'next-padding
-   (ly:output-def-lookup layout 'between-system-padding)))
-
-
-(define (line-minimum-distance line next-line layout ignore-padding)
-  "Minimum distance between `line' reference position and `next-line'
- reference position. If next-line is #f, return #f."
-  (and next-line
-       (max 0 (- (+ (interval-end (paper-system-extent next-line Y))
-		    (if ignore-padding 0 (line-next-padding line next-line layout)))
-		 (interval-start (paper-system-extent line Y))))))
-
-(define (line-ideal-distance line next-line layout ignore-padding)
-  "Ideal distance between `line' reference position and `next-line'
- reference position. If next-line is #f, return #f."
-  (and next-line
-       (+ (max 0 (- (+ (interval-end (paper-system-staff-extents next-line))
-		       (if ignore-padding 0 (line-next-padding line next-line layout)))
-		    (interval-start (paper-system-staff-extents line))))
-	  (line-next-space line next-line layout))))
-
-(define (first-line-position line layout)
-  "Position of the first line on page"
-  (max (+ (ly:output-def-lookup layout 'page-top-space)
-	  (interval-end (paper-system-staff-extents line)))
-       (interval-end (paper-system-extent line Y))))
-
-(define (line-ideal-relative-position line prev-line layout ignore-padding)
-  "Return ideal position of `line', relative to `prev-line' position.
-  `prev-line' can be #f, meaning that `line' is the first line."
-  (if (not prev-line)
-      ;; first line on page
-      (first-line-position line layout)
-      ;; not the first line on page
-      (max (line-minimum-distance prev-line line layout ignore-padding)
-	   (line-ideal-distance prev-line line layout ignore-padding))))
-
-(define (line-minimum-relative-position line prev-line layout ignore-padding)
-  "Return position of `line', relative to `prev-line' position.
-  `prev-line' can be #f, meaning that `line' is the first line."
-  (if (not prev-line)
-      ;; first line on page
-      (first-line-position line layout)
-      ;; not the first line on page
-      (line-minimum-distance prev-line line layout ignore-padding)))
-
-(define (line-minimum-position-on-page line prev-line prev-position page)
-  "If `line' fits on `page' after `prev-line', which position on page is
-  `prev-position', then return the line's postion on page, otherwise #f.
-  `prev-line' can be #f, meaning that `line' is the first line."
-  (let* ((layout (ly:paper-book-paper (page-property page 'paper-book)))
-         (position (+ (line-minimum-relative-position line prev-line layout #f)
-                      (if prev-line prev-position 0.0)))
-         (bottom-position (- position
-                             (interval-start (paper-system-extent line Y)))))
-    (and (or (not prev-line)
-             (< bottom-position (page-printable-height page)))
-         position)))
-
-(define (stretchable-line? line)
-  "Say whether a system can be stretched."
-  (not (or (ly:prob-property? line 'is-title)
-	   (let ((system-extent (paper-system-staff-extents line)))
-	     (= (interval-start system-extent)
-		(interval-end	system-extent))))))
-
-(define (page-maximum-space-to-fill page lines paper)
-  "Return the space between the first line top position and the last line
-  bottom position. This constitutes the maximum space to fill on `page'
-  with `lines'."
-  (let ((last-line (car (last-pair lines))))
-    (- (page-printable-height page)
-       (first-line-position (first lines) paper)
-       (ly:prob-property last-line
-			 'bottom-space 0.0)
-       (- (interval-start (paper-system-extent last-line Y))))))
-
-(define (page-maximum-space-left page)
-  (let ((paper (ly:paper-book-paper (page-property page 'paper-book))))
-    (let bottom-position ((lines (page-property page 'lines))
-                          (prev-line #f)
-                          (prev-position #f))
-      (if (null? lines)
-          (page-printable-height page)
-          (let* ((line (first lines))
-                 (position (line-minimum-position-on-page
-                            line prev-line prev-position page)))
-            (if (null? (cdr lines))
-                (and position
-                     (- (page-printable-height page)
-                        (- position
-                           (interval-start (paper-system-extent line Y)))))
-                (bottom-position (cdr lines) line position)))))))
-
-;;;
-;;; Utilities for distributing systems on a page
-;;;
-
-(define (space-systems space-to-fill lines ragged paper ignore-padding)
-  "Compute lines positions on page: return force and line positions as a pair.
- force is #f if lines do not fit on page."
-  (let* ((empty-stencil (ly:make-stencil '() '(0 . 0) '(0 . 0)))
-	 (empty-prob (ly:make-prob 'paper-system (list `(stencil . ,empty-stencil))))
-	 (cdr-lines (append (cdr lines)
-			    (if (<= (length lines) 1)
-				(list empty-prob)
-				'())))
-	 (springs (map (lambda (prev-line line)
-			 (list (line-ideal-distance prev-line line paper ignore-padding)
-			       (/ 1.0 (line-next-space prev-line line paper))))
-		       lines
-		       cdr-lines))
-	 (rods (map (let ((i -1))
-		      (lambda (prev-line line)
-			(set! i (1+ i))
-			(list i (1+ i)
-			      (line-minimum-distance prev-line line paper ignore-padding))))
-		       lines
-		       cdr-lines))
-	 (space-result
-	  (ly:solve-spring-rod-problem springs rods space-to-fill ragged)))
-    (cons (car space-result)
-	  (map (let ((topskip (first-line-position (first lines) paper)))
-		 (lambda (y)
-		   (+ y topskip)))
-	       (cdr space-result)))))
-
-(define (make-page-from-systems paper-book lines page-number ragged last)
-  "Return a new page, filled with `lines'."
-  (let* ((page (make-page paper-book
-			  'lines lines
-			  'page-number page-number
-			  'is-last last))
-	 (posns (if (null? lines)
-		    (list)
-		    (let* ((paper (ly:paper-book-paper paper-book))
-			   (space-to-fill (page-maximum-space-to-fill
-					    page lines paper))
-			   (spacing (space-systems space-to-fill lines ragged paper #f)))
-		      (if (or (not (car spacing)) (inf? (car spacing)))
-			  (cdr (space-systems space-to-fill lines ragged paper #t))
-			  (cdr spacing))))))
-    (page-set-property! page 'configuration posns)
-    page))
-
-;;;
-;;; Page breaking function
-;;;
-
 ;; Optimal distribution of
 ;; lines over pages; line breaks are a given.
 
@@ -223,147 +152,309 @@
 ;; - separate function for word-wrap style breaking?
 ;; - ragged-bottom? ragged-last-bottom?
 
-(define (get-path node done)
-  "Follow NODE.PREV, and return as an ascending list of pages. DONE
+(define-public (optimal-page-breaks lines paper-book)
+  "Return pages as a list starting with 1st page. Each page is a 'page Prob."
+
+  (define MAXPENALTY 1e9)
+  (define paper (ly:paper-book-paper paper-book))
+
+  ;; ugh.
+  (define page-alist (layout->page-init (ly:paper-book-paper paper-book))) 
+  (define scopes (ly:paper-book-scopes paper-book))
+  (define force-equalization-factor #f)
+  (define (get-path node done)
+    
+    "Follow NODE.PREV, and return as an ascending list of pages. DONE
 is what have collected so far, and has ascending page numbers."
-  (if (page? node)
-      (get-path (page-prev node) (cons node done))
-      done))
-
-(define (combine-penalties force user best-paths
-			   inter-system-space force-equalization-factor)
-  (let* ((prev-force (if (null? best-paths)
-			 0.0
-			 (page-force (car best-paths))))
-	 (prev-penalty (if (null? best-paths)
+
+    (if (page? node)
+	(get-path (page-prev node) (cons node done))
+	done))
+
+  (define (combine-penalties force user best-paths)
+    (let* ((prev-force (if (null? best-paths)
 			   0.0
-			   (page-penalty (car best-paths))))
+			   (page-force (car best-paths))))
+	   (prev-penalty (if (null? best-paths)
+			     0.0
+			     (page-penalty (car best-paths))))
+	 (inter-system-space (ly:output-def-lookup paper 'between-system-space))
 	 (relative-force (/ force inter-system-space))
 	 (abs-relative-force (abs relative-force)))
-    (+ (* abs-relative-force (+ abs-relative-force 1))
-       prev-penalty
-       (* force-equalization-factor (/ (abs (- prev-force force))
-				       inter-system-space))
-       user)))
-
-(define (walk-paths done-lines best-paths current-lines last current-best
-		    paper-book page-alist)
-  "Return the best optimal-page-break-node that contains
-CURRENT-LINES. DONE-LINES.reversed ++ CURRENT-LINES is a consecutive
+
+      (+ (* abs-relative-force (+ abs-relative-force 1))
+	 prev-penalty
+	 (* force-equalization-factor (/ (abs (- prev-force force))
+					 inter-system-space))
+	 user)))
+
+  (define (space-systems page-height lines ragged?)
+    (let* ((global-inter-system-space
+	    (ly:output-def-lookup paper 'between-system-space))
+	   (top-space
+	    (ly:output-def-lookup paper 'page-top-space))
+	   (global-fixed-dist (ly:output-def-lookup paper 'between-system-padding))
+	   
+	   (system-vector (list->vector
+			   (append lines
+				   (if (= (length lines) 1)
+				       '(#f)
+				       '()))))
+	   (staff-extents
+	    (list->vector
+	     (append (map paper-system-staff-extents lines)
+		     (if (= (length lines) 1)
+			 '((0 . 0))
+			 '()))))
+
+	   (real-extents
+	    (list->vector
+	     (append
+	      (map
+	       (lambda (sys) (paper-system-extent sys Y)) lines)
+	      (if (= (length lines) 1)
+		  '((0 .  0))
+		  '()))))
+	   
+	   (system-count (vector-length real-extents))
+	   (topskip (max
+		     (+
+		      top-space
+		      (interval-end (vector-ref staff-extents 0)))
+		     (interval-end (vector-ref real-extents 0))
+		     ))
+	   (last-system (vector-ref system-vector (1- system-count)))
+	   (bottom-space (if (ly:prob? last-system)
+			     (ly:prob-property last-system 'bottom-space 0.0)
+			     0.0))
+	   (space-left (- page-height
+			  bottom-space
+			  (apply + (map interval-length
+					(vector->list real-extents)))))
+
+	   (space (- page-height
+		     topskip
+		     bottom-space
+		     (-  (interval-start
+			  (vector-ref real-extents (1- system-count))))))
+
+	   (calc-spring
+	    (lambda (idx)
+	      (let* (
+		     (upper-system (vector-ref system-vector idx))
+		     (between-space (ly:prob-property upper-system 'next-space
+							      global-inter-system-space))
+		     (fixed-dist (ly:prob-property upper-system 'next-padding
+							   global-fixed-dist))
+		     
+		     (this-system-ext (vector-ref staff-extents idx))
+		     (next-system-ext (vector-ref staff-extents (1+ idx)))
+		     (fixed (max 0 (- (+ (interval-end next-system-ext)
+					 fixed-dist)
+				      (interval-start this-system-ext))))
+		     (title1? (and (vector-ref system-vector idx)
+				   (paper-system-title? (vector-ref system-vector idx)
+							     )))
+		     (title2? (and
+			       (vector-ref system-vector (1+ idx))
+			       (paper-system-title? (vector-ref system-vector (1+ idx)))))
+		     (ideal (+
+			     (cond
+			      ((and title2? title1?)
+			       (ly:output-def-lookup paper 'between-title-space))
+			      (title1?
+			       (ly:output-def-lookup paper 'after-title-space))
+			      (title2?
+			       (ly:output-def-lookup paper 'before-title-space))
+			      (else between-space))
+			     fixed))
+		     (hooke (/ 1 (- ideal fixed))))
+		(list ideal hooke))))
+
+	   (springs (map calc-spring (iota (1- system-count))))
+	   (calc-rod
+	    (lambda (idx)
+	      (let* (
+		     (upper-system (vector-ref system-vector idx))
+		     (fixed-dist (ly:prob-property upper-system 'next-padding
+							   global-fixed-dist))
+		     (this-system-ext (vector-ref real-extents idx))
+		     (next-system-ext (vector-ref real-extents (1+ idx)))
+		     
+		     (distance (max  (- (+ (interval-end next-system-ext)
+					   fixed-dist)
+					(interval-start this-system-ext)
+					) 0))
+		     (entry (list idx (1+ idx) distance)))
+		entry)))
+	   (rods (map calc-rod (iota (1- system-count))))
+
+	   ;; we don't set ragged based on amount space left.
+	   ;; ragged-bottomlast = ##T is much more predictable
+	   (result (ly:solve-spring-rod-problem
+		    springs rods space
+		    ragged?))
+
+	   (force (car result))
+	   (positions
+	    (map (lambda (y)
+		   (+ y topskip))
+		 (cdr  result))))
+
+      (if #f ;; debug.
+	  (begin
+	    (display (list "\n# systems: " system-count
+			   "\nreal-ext" real-extents "\nstaff-ext" staff-extents
+			   "\ninterscore" global-inter-system-space
+			   "\nspace-left" space-left
+			   "\nspring,rod" springs rods
+			   "\ntopskip " topskip
+			   " space " space
+			   "\npage-height" page-height
+			   "\nragged" ragged?
+			   "\nforce" force
+			   "\nres" (cdr result)
+			   "\npositions" positions "\n"))))
+
+      (cons force positions)))
+
+  (define (walk-paths done-lines best-paths current-lines last? current-best)
+    "Return the best optimal-page-break-node that contains
+CURRENT-LINES.  DONE-LINES.reversed ++ CURRENT-LINES is a consecutive
 ascending range of lines, and BEST-PATHS contains the optimal breaks
 corresponding to DONE-LINES.
 
 CURRENT-BEST is the best result sofar, or #f."
-  (let* ((paper (ly:paper-book-paper paper-book))
-	 (this-page (make-page
-		     paper-book
-		     'is-last last
-		     'page-number (if (null? best-paths)
-				      (ly:output-def-lookup paper 'first-page-number)
-				      (1+ (page-page-number (first best-paths))))))
-	 (ragged-all (eq? #t (ly:output-def-lookup paper 'ragged-bottom)))
-	 (ragged-last (eq? #t (ly:output-def-lookup paper 'ragged-last-bottom)))
-	 (ragged (or ragged-all (and ragged-last last)))
-	 (space-to-fill (page-maximum-space-to-fill this-page current-lines paper))
-	 (vertical-spacing (space-systems space-to-fill current-lines ragged paper #f))
-	 (satisfied-constraints (car vertical-spacing))
-	 (force (if satisfied-constraints
-		    (if (and last ragged-last)
-			0.0
-			satisfied-constraints)
-		    10000))
-	 (positions (cdr vertical-spacing))
-	 (get-break-penalty (lambda (sys)
-			      (ly:prob-property sys 'penalty 0.0)))
-	 (user-nobreak-penalties (- (apply + (filter negative?
-						     (map get-break-penalty
-							  (cdr current-lines))))))
-	 (user-penalty (+ (max (get-break-penalty (car current-lines)) 0.0)
-			  user-nobreak-penalties))
-	 (total-penalty (combine-penalties
-			 force user-penalty best-paths
-			 (ly:output-def-lookup paper 'between-system-space)
-			 (ly:output-def-lookup paper 'verticalequalizationfactor 0.3)))
-	 (new-best (if (or (not current-best)
-			   (and satisfied-constraints
-				(< total-penalty (page-penalty current-best))))
-		       (begin
-			 (map (lambda (x)
-				(page-set-property! this-page
-						    (car x)
-						    (cdr x)))
-			      (list (cons 'prev (if (null? best-paths)
-						    #f
-						    (car best-paths)))
-				    (cons 'lines current-lines)
-				    (cons 'force force)
-				    (cons 'configuration positions)
-				    (cons 'penalty total-penalty)))
-			 this-page)
-		       current-best)))
-    (if #f ;; debug
-	(display
-	 (list
-	  "\nuser pen " user-penalty
-	  "\nsatisfied-constraints" satisfied-constraints
-	  "\nlast? " last "ragged?" ragged
-	  "\nis-better " is-better " total-penalty " total-penalty "\n"
-	  "\nconfig " positions
-	  "\nforce " force
-	  "\nlines: " current-lines "\n")))
-    (if #f ; debug
-	(display (list "\nnew-best is " (page-lines new-best)
-		       "\ncontinuation of "
-		       (if (null? best-paths)
-			   "start"
-			   (page-lines (car best-paths))))))
-    (if (and (pair? done-lines)
-	     ;; if this page is too full, adding another line won't help
-	     satisfied-constraints)
-	(walk-paths (cdr done-lines) (cdr best-paths)
-		    (cons (car done-lines) current-lines)
-		    last new-best
-		    paper-book page-alist)
-	new-best)))
-
-(define (walk-lines done best-paths todo paper-book page-alist)
-  "Return the best page breaking as a single
+
+    (let* ((this-page-num (if (null? best-paths)
+                              (ly:output-def-lookup paper 'first-page-number)
+                              (1+ (page-page-number (car best-paths)))))
+
+	   (this-page (make-page
+		       page-alist
+		       'paper-book paper-book
+		       'is-last last?
+		       'page-number this-page-num))
+
+	   (ragged-all? (eq? #t (ly:output-def-lookup paper 'ragged-bottom)))
+	   (ragged-last? (eq? #t (ly:output-def-lookup paper 'ragged-last-bottom)))
+	   (ragged? (or ragged-all?
+			(and ragged-last?
+			     last?)))
+           (height (page-printable-height this-page))
+	   (vertical-spacing (space-systems height current-lines ragged?))
+	   
+	   (satisfied-constraints (car vertical-spacing))
+           (force (if satisfied-constraints
+		      (if (and last? ragged-last?)
+			  0.0
+			  satisfied-constraints)
+		      10000))
+	   (positions (cdr vertical-spacing))
+	   (get-break-penalty (lambda (sys)
+				(ly:prob-property sys 'penalty 0.0)))
+	   (user-nobreak-penalties
+	    (-
+	     (apply + (filter negative?
+			      (map get-break-penalty
+				   (cdr current-lines))))))
+           (user-penalty
+	    (+
+	     (max (get-break-penalty (car current-lines)) 0.0)
+	     user-nobreak-penalties))
+	   
+           (total-penalty (combine-penalties
+                           force user-penalty
+			   best-paths))
+
+           (is-better (or
+		       (not current-best)
+		       (and
+			satisfied-constraints
+			(< total-penalty (page-penalty current-best)))))
+           (new-best (if is-better
+			 (begin
+			   (map
+			    (lambda (x)
+			      (page-set-property! this-page
+						  (car x)
+						  (cdr x)))
+			    (list
+			     (cons 'prev (if (null? best-paths)
+					     #f
+					     (car best-paths)))
+			     (cons 'lines current-lines)
+			     (cons 'force force)
+			     (cons 'configuration positions)
+			     (cons 'penalty total-penalty)))
+			   this-page)
+                         current-best)))
+
+;;      (display total-penalty) (newline)
+      (if #f ;; debug
+          (display
+           (list
+            "\nuser pen " user-penalty
+	    "\nsatisfied-constraints" satisfied-constraints
+	    "\nlast? " last? "ragged?" ragged?
+            "\nis-better " is-better " total-penalty " total-penalty "\n"
+	    "\nconfig " positions
+            "\nforce " force
+	    "\nlines: " current-lines "\n")))
+
+      (if #f ; debug
+	  (display (list "\nnew-best is " (page-lines new-best)
+			 "\ncontinuation of "
+			 (if (null? best-paths)
+			     "start"
+			     (page-lines (car best-paths))))))
+
+      (if (and (pair? done-lines)
+               ;; if this page is too full, adding another line won't help
+               satisfied-constraints)
+          (walk-paths (cdr done-lines) (cdr best-paths)
+                      (cons (car done-lines) current-lines)
+                      last? new-best)
+	  new-best)))
+
+  (define (walk-lines done best-paths todo)
+    "Return the best page breaking as a single
 page node for optimally breaking TODO ++
 DONE.reversed. BEST-PATHS is a list of break nodes corresponding to
 DONE."
-  (if (null? todo)
-      (car best-paths)
-      (let* ((this-line (car todo))
-	     (last (null? (cdr todo)))
-	     (next (walk-paths done best-paths (list this-line) last #f
-			       paper-book page-alist)))
-	(walk-lines (cons this-line done)
-		    (cons next best-paths)
-		    (cdr todo)
-		    paper-book
-		    page-alist))))
-
-(define-public (optimal-page-breaks paper-book)
-  "Return pages as a list starting with 1st page. Each page is a 'page Prob."
-  (let* ((paper (ly:paper-book-paper paper-book))
-	 (lines (ly:paper-book-systems paper-book))
-	 (page-alist (layout->page-init paper)) 
-	 (force-equalization-factor (ly:output-def-lookup
-				     paper 'verticalequalizationfactor 0.3)))
-    (ly:message (_ "Calculating page breaks..."))
-    (let* ((best-break-node (walk-lines '() '() lines paper-book page-alist))
-	   (break-nodes (get-path best-break-node '())))
-      (page-set-property! (car (last-pair break-nodes)) 'is-last #t)
-      (if #f; (ly:get-option 'verbose)
-	  (begin
-	    (display (list
-		      "\nbreaks: " (map (lambda (node)
-					  (ly:prob-property (car (page-lines node))
-							    'number))
-					break-nodes)
-		      "\nsystems " (map page-lines break-nodes)
-		      "\npenalties " (map page-penalty break-nodes)
-		      "\nconfigs " (map page-configuration break-nodes)))))
-      ;; construct page stencils.
-      (for-each page-stencil break-nodes)
-      break-nodes)))
+    
+    (if (null? todo)
+	(car best-paths)
+	(let* ((this-line (car todo))
+	       (last? (null? (cdr todo)))
+	       (next (walk-paths done best-paths (list this-line) last? #f)))
+
+	  ;; (display "\n***************")
+	  (walk-lines (cons this-line done)
+		      (cons next best-paths)
+		      (cdr todo)))))
+
+  (define (line-number node)
+    (ly:prob-property (car (page-lines node)) 'number))
+  
+  (ly:message (_ "Calculating page breaks..."))
+  (set! force-equalization-factor
+	(ly:output-def-lookup paper 'verticalequalizationfactor 0.3))
+  
+  (let* ((best-break-node (walk-lines '() '() lines))
+	 (break-nodes (get-path best-break-node '())))
+
+    (page-set-property! (car (last-pair break-nodes)) 'is-last #t)
+    (if #f; (ly:get-option 'verbose)
+	(begin
+	  (display (list
+		    "\nbreaks: " (map line-number break-nodes))
+		   "\nsystems " (map page-lines break-nodes)
+		   "\npenalties " (map page-penalty break-nodes)
+		   "\nconfigs " (map page-configuration break-nodes))))
+
+    ;; construct page stencils.
+    (for-each page-stencil break-nodes)
+    (post-process-pages paper break-nodes)
+    
+    break-nodes))